容积旋转调强放疗与固定野调强放疗在巨块型宫颈癌根治性放疗中的剂量学比较

Dosimetric comparison of volumetric rotary intensity-modulated radiotherapy and fixed field-intensity-modulated radiotherapy in radiotherapy for large and advanced cervical cancer

目的:比较容积旋转调强放疗(VMAT)与7野固定野调强放疗(7IMRT)在中晚期巨块型宫颈癌放射治疗中的剂量学差异。方法:选取24例局部肿瘤大于4 cm的中晚期宫颈癌患者,对同个CT图像分别制作VAMT计划和7IMRT计划。比较两种计划的靶区适型性指数(CI)、均匀性指数(HI)、正常组织的剂量学差异、机器跳数(MU)及治疗时间。结果:采用VMAT放疗技术的肿瘤靶区CI为0.912±0.008,与IMRT相当(0.911±0.006)(P=0.426),而VMAT的HI为1.092±0.034,优于IMRT(1.10±0.034)(P=0.001)。VAMT技术膀胱的V30、V40,直肠的V30、V45,肠管的V30、V40、V45,脊髓V20、V30、V35、Dmax均优于7IMRT,且差异有统计学意义,但肠管的V10VAMT高于IMRT,差异有统计学意义;双侧股骨头剂量分布差异无统计学意义。VMAT技术MU较7IMRT减少59.8%,平均治疗时间减少78.76%。结论:VAMT是巨块型宫颈癌患者根治性放疗的较好选择之一。

Objective:To compare the dosimetric differences between volumetric rotary intensity-modulated radiotherapy(VMAT)and 7 fixed-field intensity-modulated radiotherapy(7IMRT)in the radiotherapy of large and advanced cervical cancer.Methods:Twenty-four patients with advanced cervical cancer with a local tumor larger than 4 cm were selected,and VAMT plan and 7IMRT plan were made on the same CT.The target conformity index(CI),homogeneity index(HI),dosimetric difference of normal tissue,number of machine units(MU)and treatment time of the two plans were compared.Results:The CI of the tumor target area using VMAT was 0.912±0.008,which was equivalent to IMRT(0.911±0.006)(P=0.426),while the HI of VAMT was 1.092±0.034,which was better than IMRT(1.10±0.034)(P=0.001).The V30 and V40 of the bladder,V30 and V45 of the rectum,V30,V40 and V45 of the intestine,V20,V30,V35 and D max of the spinal cord of VMAT plan were all better than those of 7IMRT plan,but V10 of the intestine was higher than 7IMRT,and the differences were all statistical significance.There was no statistical difference in the dose distribution of the bilateral femoral heads.The MU of VMAT decreased by 59.8%compared with 7IMRT,and the average treatment time was reduced by 78.76%.Conclusion:VAMT is one of the better choices for radical radiotherapy in patients with massive cervical cancer.